Different Types Of Filaments Research Articles

3D Printing and Biodegradable Polymers

Abstract 3D printing technology has a wide range of applications in many industries, including automotive, aerospace, biomedical, electronics and packaging, requiring different types of filaments to be used in producing 3D printed objects. The most commonly used materials are metals, ceramics, composites and plastics of which the latter are most available. Since it is necessary to reduce pollution caused by waste from conventional petroleum-based plastics, biodegradable polymers made from renewable resources or produced synthetically have gained in importance recently. Polylactic acid, poly(butylene succinate), thermoplastic starch, poly(butylene adipate co-terephthalate) and polycaprolactone are well-known representatives of this group of materials. They possess desirable properties for 3D printing which make them promising materials in many areas of applications.

Repetitive recycling effects on mechanical characteristics of poly‐lactic acid and PLA/spent coffee grounds composite used for 3D printing filament

AbstractDue to its biodegradability, biocompatibility, and mechanical properties, poly‐lactic acid (PLA) is a leading biomaterial for numerous applications, especially for fused deposition modeling and fused filament fabrication. Nonetheless, the absence of a comprehensive recycling strategy may emerge as a significant source of plastic pollution in the future. Indeed, the polymer undergoes deterioration during melt recycling, resulting in a decrease in some mechanical properties that can compromise recyclability. To improve the properties of recycled PLA, the utilization of organic fillers coming from renewable materials can be considered as a sustainable solution. The objective of this work is then to evaluate the effect of recycling (reprocessing) on a virgin raw material as well as on biocomposites based on spent coffee grounds (incorporating 5% of spend coffee grounds in weight). The different types of filaments are extruded and re‐extruded and characterized under tensile, melt flow index, and hardness tests. The results show that the increase in the number of extrusions whether for virgin PLA or the composite contributes to the diameter fluctuation. Regarding the tensile properties, the rise in the frequency of recycling shows a weakness in the tensile strength and the elongation at break. On the other hand, Young's modulus values exhibit fluctuations. Concerning the addition of the spent coffee grounds filler, no major enhancement is observed in the tensile strength and the elongation at break, which is attributed to the poor adhesion between the matrix and the filler. The recycling process affects the hardness values of PLA, leading to an increase in these values, as well as those of the composite, which can be associated with the increased crystallinity caused by the recycling process and the SCG incorporation.Highlights Recycling and reusability strategy for poly‐lactic acid (PLA) and PLA/spent coffee grounds (SCG) filaments. Assessment of recycling effects on PLA and PLA/SCG. Mechanical characterization through tensile and hardness testing.

Investigation of wettability and wear properties on 3D printed Polylactic acid/Molybdenum disulfide-Silicon carbide polymeric composite for sustainable biomedical applications

In the present work, investigations of the wettability, wear, and morphological study on 3D-printed polylactic acid (PLA)/molybdenum disulfide (MoS2)-silicon carbide (SiC) based composite have been performed. In the first stage, the PLA/MoS2-SiC composite was fabricated from the different types of filaments of 1.75 ± 0.10 mm size by taking MoS2-SiC as reinforcement at various extrusion temperatures (150°C–160°C) and screw rotational speed (3–7 r/min) of the extruder setup. The Taguchi L9 orthogonal array was used to design the experiments for 3D printing by varying the filament type, range of nozzle temperature (200°C–210°C), and infill density (40%–90%). The pin-on-disk (POD) setup was used for measuring specific wear rate (SWR) and showed the lowest value of 0.00141 g/N-m when composites were 3D printed by taking filaments manufactured at the parametric combination of 160°C extruder temperature and 7 r/min rotational speed, while 3D printed at 210°C nozzle temperature and 40% infill density. Contact angle (CA) values indicated that the reinforcement of MoS2 and SiC in PLA resulted in hydrophilic surface formation due to morphology and increased roughness (including mean roughness (Sa), mean root square of the Z data (Sq), and the highest peak (Sz)). The significantly increased surface free energy (SFE) of MoS2-SiC-reinforced PLA composite compared to pure PLA was reported which makes the prepared composite a promising candidate to be used for biocompatible implants with high wear resistance.

Mineralogical and geochemical features of the Sirna Mn‐Fe deposit in the Kurdistan region, northeastern Iraq: Unveiling the formation of a Mn‐Fe silica gel plume via serpentinization hydrothermal mechanisms

AbstractThe study probes the mineralogical and geochemical features of manganese‐iron deposits located in the Sirna area, which is a part of the late Cretaceous Walash Group in the Zagros suture zone, situated in the Kurdistan region of northeastern Iraq. Our investigation comprised field surveys, examination of ore petrography, besides using x‐ray diffraction, SEM‐EDS analysis, x‐ray fluorescence analyses, and inductively coupled plasma mass spectrometry techniques conducted on a set of representative samples. A significant Mn‐Fe ovoidal ore body, extending across 25 meters in diameter, protrudes between the lower strata of soft gray shale and the upper strata of massive limestone within the Walash group. The deposit exhibits a distinct separation into three layers: a lower horizon characterized by abundance of oxide of silicon, an upper horizon enriched in manganese oxide, and a transition layer dominated by hematite (Fe2O3). From a geochemical perspective, there is a gradual decrease in Fe2O3 and SiO2 from the lower to the upper part of the deposit, while MnO, BaO, and SO3 demonstrate a gradual increase. The co‐association of Mn‐Fe‐mineralization in a small restricted tabular ore body suggests that they are genetically related. Within the Sirna manganese‐iron deposit, the prevalent manganese and iron mineral phases are braunite, hollandite, and hematite. Concurrently, the gangue minerals in this deposit encompass cryptocrystalline spheroidal quartz, barite, calcite, and apatite. The Sirna Mn‐Fe deposit exhibits geochemical characteristics such as elevated levels of MnO (reaching up to 68 wt.%) and significant Fe2O3 content (up to 45 wt.%) in the upper manganese and transitional iron horizons, respectively. The Co/Zn ratio (0.28), Ce/La ratio (1.78), low levels of transitional elements (Co + Ni + Cu <0.01 wt.%), and varying concentrations of Ba (up to 6.9 wt.%) suggest that the Siran Mn‐Fe deposit is likely originated from a manganese‐iron silica gel plume that separated from hydrothermal fluids linked to serpentinization. This process is thought to have occurred in the mantle wedge along subduction zone, typically within an arc tectonic environment. Moreover, the presence of remnants of micro‐organisms such as EPS layers, different types of filaments, which are densely covered by biominerals, are important evidence of microbial effect in the mineralization of Mn‐Fe in the study area.

Classification of helical polymers with deep-learning language models

Many macromolecules in biological systems exist in the form of helical polymers. However, the inherent polymorphism and heterogeneity of samples complicate the reconstruction of helical polymers from cryo-EM images. Currently, available 2D classification methods are effective at separating particles of interest from contaminants, but they do not effectively differentiate between polymorphs, resulting in heterogeneity in the 2D classes. As such, it is crucial to develop a method that can computationally divide a dataset of polymorphic helical structures into homogenous subsets. In this work, we utilized deep-learning language models to embed the filaments as vectors in hyperspace and group them into clusters. Tests with both simulated and experimental datasets have demonstrated that our method – HLM (Helical classification with Language Model) can effectively distinguish different types of filaments, in the presence of many contaminants and low signal-to-noise ratios. We also demonstrate that HLM can isolate homogeneous subsets of particles from a publicly available dataset, resulting in the discovery of a previously unreported filament variant with an extra density around the tau filaments.

Exploring 3D printing techniques for the hybrid fabrication of discrete topology optimized structures

The application of topology optimization methods in architecture, while useful for conceptual design explorations, seems to be limited by the practical realization of continuum-type design outcomes. One way to overcome this limitation is setting up design and fabrication techniques, through which continuum domains become discrete structures. This study investigates to which extent discrete optimized systems can be built using a hybrid approach combining 3D printing and analogue fabrication techniques. The procedure is based on an algorithm in Grasshopper (Rhinoceros) that translates continuum topologies obtained in MATLAB into discrete systems, providing alternatives depending on the targeted volume fraction, the intended surface smoothness of the structural components and building material. The study focuses on fabrication aspects and structural performance of discrete structures using 3D printed nodes. Experimental tests evaluate the compressive strength of different types of filaments with varied infill percentages. Final prototypes are fabricated using a hybrid technique involving the use of 3D printed nodes to assemble bar-arrays comprising wooden members. Results provide a critical appraisal of the limitations and potentialities of 3D printing for hybrid fabrication of real scale structures.

Fused Filament Fabrication of ONYX-Based Composites Coated with Aluminum Powders: a Preliminary Analysis on Feasibility and Characterization

Polymer-based AM methods are the most mature additive technologies for their versatility and variety of products obtainable. The addition of fibre reinforcement can also confer to the manufactures produced good mechanical properties. Unfortunately, several applications are still precluded because polymers cannot guarantee appropriate electrical conductivity, erosion resistance and operating temperature. Aiming to overcome these issues, the metallization of the surfaces emerges as a possible solution. Unfortunately, thermoplastic polymers exhibit thermosensitive behaviour and run the risk of being damaged when traditional metallization techniques, which require the melting of metal powders which will act as a protective coating. For this reason, studies have focused on Cold Gas Dynamic Spray, an additive manufacturing technology, which exploits kinetic energy to favour the adhesion of metal particles rather than the increase in temperature. In this work, a first attempt is made to verify the feasibility of cold spray coatings on 3D printed composite substrates, produced by means of Fused Filament Fabrication (FFF) technique. FFF technology allows the deposition of two different types of filaments by using a double extruder. These composite fibres within 3D printed parts manage to give the object a resistance comparable to that of a metal part with lower production cost and a high degree of automation. These structures, made of ONYX, a Nylon matrix in which short carbon fibres are dispersed, and reinforced with long carbon fibres, are designed to better fit the CS deposition. Aluminium coatings have been produced and a characterization campaign has been carried on.

Pseudohyphal Growth of the Emerging Pathogen Candida auris Is Triggered by Genotoxic Stress through the S Phase Checkpoint.

The morphogenetic switching between yeast cells and filaments (true hyphae and pseudohyphae) is a key cellular feature required for full virulence in many polymorphic fungal pathogens, such as Candida albicans In the recently emerged yeast pathogen Candida auris, occasional elongation of cells has been reported. However, environmental conditions and genetic triggers for filament formation have remained elusive. Here, we report that induction of DNA damage and perturbation of replication forks by treatment with genotoxins, such as hydroxyurea, methyl methanesulfonate, and the clinically relevant fungistatic 5-fluorocytosine, cause filamentation in C. auris The filaments formed were characteristic of pseudohyphae and not parallel-sided true hyphae. Pseudohyphal growth is apparently signaled through the S phase checkpoint and, interestingly, is Tup1 independent in C. auris Intriguingly, the morphogenetic switching capability is strain specific in C. auris, highlighting the heterogenous nature of the species as a whole.IMPORTANCECandida auris is a newly emerged fungal pathogen of humans. This species was first reported in 2009 when it was identified in an ear infection of a patient in Japan. However, despite intense interest in this organism as an often multidrug-resistant fungus, there is little knowledge about its cellular biology. During infection of human patients, fungi are able to change cell shape from ellipsoidal yeast cells to elongated filaments to adapt to various conditions within the host organism. There are different types of filaments, which are triggered by reactions to different cues. Candida auris fails to form filaments when exposed to triggers that stimulate yeast filament morphogenesis in other fungi. Here, we show that it does form filaments when its DNA is damaged. These conditions might arise when Candida auris cells interact with host immune cells or during growth in certain host tissues (kidney or bladder) or during treatment with antifungal drugs.

In Situ TEM Observation of Dynamic Switching Behaviors in Vrram

Resistive random access memory (RRAM) is considered as a promising candidate for the next-generation nonvolatile memories (NVM) due to its high storage density, reduced power consumption, and fast switching speed. Transition metal oxides are widely utilized to RRAM as insulator, which exhibit stable structure, high endurance and retention, and shrinking ability under several nanometers. In order to realize higher endurance and stability while reducing the size, knowing the mechanism of filaments formation and the interaction between adjacent nanodevices are essential. In this work, three-dimensional vertical RRAM (VRRAM) array architectures were built to access and organize data, which are expected to high density application potential. In our simple MIM structure, ZnO is the insulator, and Ag and Pt are served as active electrode and inert electrode, respectively. Each electrodes intersection contains two types of RRAM devices (Ag/ZnO/Pt, Pt/ZnO/Pt). By utilizing in-situ transmission electron microscope (TEM), we could observe the dynamic switching behaviors of two neighboring devices and realize the interaction between them. While the devices sizes scale down to few nanometers scale, the evolution of different types of filaments provides important information to improve the stability and performance of the devices.

Impact of activated sludge ozonation on filamentous bacteria viability and possible added benefits

ABSTRACTOzone was applied to return activated sludge in full-scale to study how ozone impacts filamentous bacteria viability (Live/Dead®). Additionally, the ozonated sludges were subjected to anaerobic digestion trials and analysis of micropollutants (MPs). Ozone treatment (3–4.8 g O3/kg total suspended solids) improved the settling properties of the sludge by lowering the diluted sludge volume with 7–35%. Ozone inactivated filamentous bacteria outside the floc structures and the fraction of inactivated filaments increased with an increasing ozone dose. It was observed that ozone treatment may act selectively towards different types of filaments. With respect to the two dominating morphotypes present, Type 0041 filamentous bacteria were found to be more resistant to ozone attack than Microthrix parvicella. Thus, higher ozone doses may be required to mitigate sludge bulking caused by Type 0041 filaments. No effects could be discerned by ozone addition on neither the methane production of the sludge nor on the concentrations of MPs analysed for this study. The lack of effect on both methane production and micropollutant removal was deemed to be caused by insufficient ozone doses.

Arabidopsis vegetative actin isoforms, AtACT2 and AtACT7, generate distinct filament arrays in living plant cells

Flowering plants express multiple actin isoforms. Previous studies suggest that individual actin isoforms have specific functions; however, the subcellular localization of actin isoforms in plant cells remains obscure. Here, we transiently expressed and observed major Arabidopsis vegetative actin isoforms, AtACT2 and AtACT7, as fluorescent-fusion proteins. By optimizing the linker sequence between fluorescent protein and actin, we succeeded in observing filaments that contained these expressed actin isoforms fused with green fluorescent protein (GFP) in Arabidopsis protoplasts. Different colored fluorescent proteins fused with AtACT2 and AtACT7 and co-expressed in Nicotiana benthamiana mesophyll cells co-polymerized in a segregated manner along filaments. In epidermal cells, surprisingly, AtACT2 and AtACT7 tended to polymerize into different types of filaments. AtACT2 was incorporated into thinner filaments, whereas AtACT7 was incorporated into thick bundles. We conclude that different actin isoforms are capable of constructing unique filament arrays, depending on the cell type or tissue. Interestingly, staining patterns induced by two indirect actin filament probes, Lifeact and mTalin1, were different between filaments containing AtACT2 and those containing AtACT7. We suggest that filaments containing different actin isoforms bind specific actin-binding proteins in vivo, since the two probes comprise actin-binding domains from different actin-binding proteins.

SYMULATOR ŹRÓDŁA ELEKTRONÓW Z GORĄCĄ KATODĄ

W niniejszej pracy opisany został symulator źródła elektronów z gorącą katodą bazujący na modelu statycznym źródła. Został on zaprojektowany w ogólnym przypadku dla różnych rodzajów katod używanych w przyrządach próżniowych w celu umożliwienia łatwych i szybkich modelowych obliczeń numerycznych użytecznych m. in. w procesie projektowania regulatorów natężenia prądu termoemisji elektronowej. Umożliwia on m.in. wyznaczenie rozkładu temperatury i natężenia prądu termoemisji elektronowej włókna w stanie ustalonym.

Simple filling patterns to model mechanical behaviour of FDM’s test pieces under torsion

This work presents how the finite element methodology has been applied to analyze the mechanical behaviour of PLA parts obtained by fused deposition with a 3D printer. Three different patterns of printed layers have been studied searching for the most accurate way to model the actual response of PLA parts in a torsion test. Nine different types of filaments have been used to make the torsion test specimens. Preliminary tasks to set up correctly the 3D printer as well as specific tensile tests carried out to know the elastic modulus of the PLA filaments are presented too. The conclusions are considered of interest to predict the mechanical behaviour of the pieces obtained by printing with fused deposition devices.

Characterization of polyurethane shape memory polymer processed by material extrusion additive manufacturing

Material extrusion additive manufacturing (MEAM), also known as three-dimensional (3D) printing, is a popular additive manufacturing technique suitable for producing 3D shapes using thermoplastic materials. The majority of companies that design and test 3D printing machines work with thermoplastic acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) filaments. It is, however, crucial to utilize different types of filaments for a broader range of applications with different mechanical property requirements. Shape memory polymers (SMPs) are smart materials that react to an applied stimulus in order to recover large strains. MEAM techniques may be used for the production of SMP-based parts, allowing for smart structures to be created in a wide variety of geometries. In this work, a commercial 3D-printer was used to produce 3D printed polyurethane-based SMP specimens. An annealing heat treatment was applied to some of the specimens. Mechanical and thermomechanical testing was conducted to study the effects of testing temperatures and annealing heat treatments on the tensile and shape memory properties of the samples. 3D printing was shown to be a suitable technique for producing SMP parts capable of retaining good shape memory characteristics. Different annealing heat treatments and test temperatures were found to have considerable effects on the SMP specimen properties. In particular, annealing the specimens at 85°C for 2h helped to improve the rate of shape recovery and the consistency of mechanical test results.

THE IMPACT OF TOOTHBRUSH FILAMENT DESIGN ON GINGIVAL HEALTH DURING HEALING. A RANDOMIZED, CONTROLLED, INVESTIGATOR-BLINDED CLINICAL TRIAL

Objectives. The primary objective of the study was to test toothbrushes with different types of filaments (conical vs. rounded) with respect to cause gingival abrasion after surgical intervention of wisdom teeth. A secondary objective was to evaluate the efficacy of plaque removal and the improvement of gingival conditions to alleviate wound healing and to avoid gingivitis. Methods. One hundred and seventy-three healthy subjects with surgical intervention of wisdom teeth participated in a randomized, single blind study and were randomly allocated to control group (standard ADA reference toothbrush) or test group (meridol® special toothbrush with conical filaments). Clinical examinations included gingival abrasion, plaque index and gingival index, and were conducted at baseline, 7 and 28 days. Results. For the gingival abrasion the mean number of lesions of all sizes was after 28 days significantly lower in the test group (p-value <0.001) compared to control group. Plaque index was not significantly different between the two groups in the last visit. At day 28 the gingival index was significantly lower in the test group (p=0.031) compared to control group. Conclusions. The toothbrush with conical filaments induced significantly less gingival abrasions than the standard ADA toothbrush and showed superior results in improving gingival health (gingival index). Both toothbrushes were comparable effective with respect to plaque removal. Clinical Relevance. Scientific rationale for study: Supra and sub-gingival biofilm leads to gingival inflammation. Post-surgical removal of the biofilm from gingival surfaces promotes healing after wisdom tooth extraction. Tooth brushing leads to gingival abrasion. Earlier investigations with toothbrushes having conical filaments suggest less gingival tissue damage. Principal findings: The results showed that the toothbrush with conical filaments caused significantly less gingival abrasions than the toothbrush with rounded filaments. Practical implications: Toothbrush filament design should be considered when choosing toothbrush for oral hygiene after oral surgery.

Characteristics of different types of filaments in resistive switching memories investigated by complex impedance spectroscopy

Complex impedance spectra of the low- and high-resistance states of Au/NiO/Pt and ITO/TiO2/ITO heterostructures were studied to probe the characteristics of conducting filaments (CFs). Different types of CFs were compared both qualitatively and quantitatively. It was demonstrated that important information of CFs, including the conducting behavior as well as the position and degree of rupture, can be obtained by analysis of the complex impedance data. We further employed this tool to explore resistive switching effect in HfO2 based heterostructures fabricated by different methods, and revealed the switching mechanisms and the effect of growth process on the properties of CFs.

Filament size influences temperature changes and brain damage following middle cerebral artery occlusion in rats.

Postischemic spontaneous hyperthermia as a complication of occlusion of the middle cerebral artery with an intraluminal filament has been observed by some authors, but many other reports do not discuss this factor. The possible reasons why some of the authors have not seen severe hyperthermia in their experiments include differences in surgical technique, the strain of animals, the type of the anesthesia, and the occluder filament. The aim of this study was to examine the changes in the core temperature of rats using different types of filaments. The middle cerebral artery was occluded for 2 h with three different types of filaments. The changes in the temperature were continuously monitored during occlusion and for the next 4 h. Groups with uncontrolled hyperthermia and with controlled normal core temperature were used. In addition, the necrotic and penumbral areas were measured 4 and 48 h after the ischemia in both groups. Spontaneous postischemic hyperthermia was detected using all types of filaments. A close correlation was found between the size of the occluder filament and the time-course and degree of hyperthermia. Moreover, the size of the filament correlated well with the size of the infarct at both 4 and 48 h after the occlusion. We suggest that filament size is a major contributor to the degree of hyperthermia and the development of brain damage in the middle cerebral artery occlusion model. Our results call attention to the need to standardize the methods used to screen for therapeutic agents for stroke.

Structural Analysis of Filaments Using the STEM

Abstract The Scanning Transmission Electron Microscope (STEM) facility at BNL is an NIH Biotechnology Research Resource and as such is available to users with suitable projects, free of charge. Currently, many of our users' projects involve studying the structures of a variety of filaments. Most of these are of biological origin, although a couple involve conducting polymers. The STEM has a long history of being used to study different types of filaments and resolving controversies about their structure. The mainstay of the STEM is mass analysis on unstained, isolated, freeze-dried samples. On these, the STEM can collect in-focus digital data directly. In a scan (8 sec. in real time) of a sample, at each of 512x512 picture elements (pixels), the number of electrons scattered into two annular detectors is recorded. For each pixel, the number of scattered electrons is directly proportional to the mass thickness in that pixel.

Electron microscopic observations of the lymphatic vessels of the mammalian testis

This paper is a report on preliminary investigations into the morphology of elastic fibers surrounding the lymphatic vessels of the testis, and it includes a description of the three-dimensional architecture of the lymph vessels and elastic fibers of the mammalian testis obtained by indirect injection of glutaraldehyde and Mercox. Different types of filaments and blind ends were observed. The filaments repeatedly divide and fuse to form the reticular networks. These networks provide a specific microenvironment for the lymphatic vascular system under different physiological and pathological conditions.

Genesis of terrestrial oncoids, Cayman Islands, British West Indies

Terrestrial oncoids, up to 4.3 mm long, are common in sinkholes that penetrate the dolostones of the Oligocene–Miocene Bluff Formation on Grand Cayman and Cayman Brac. The vaguely laminated terrestrial oncoids, which generally lack a nucleus, are formed of detrital material (micrite, clays, dolomite), calcified filaments and spores, and insect fragments. The abundant, diverse assay of microorganisms includes six different types of filaments and five different types of spores, which can be attributed to fungi, algae, and (or) cyanobacteria. Thin mats of mucus are commonly associated with the microorganisms. The microorganisms contribute to the formation of the terrestrial oncoids by (i) calcification of the filaments and spores, (ii) trapping and binding detrital material, and (iii) binding with their mucus detrital material to the surface of the oncoids.Identification of terrestrial oncoids relies on (i) the recognition of a microbial assemblage, (ii) the demonstration that the microorganisms played an active role in the their formation, and (iii) evidence that they formed in a terrestrial setting. If the microorganisms cannot be recognized because of diagenetic changes, identification must rely on the overall texture of the rock and its stratigraphic setting. Recognition of terrestrial oncoids is important because it provides additional evidence that a succession has been subaerially exposed. Terrestrial oncoids also indicate that the strata in which they occur are close to an unconformity.